There is a lot of historical baggage on this parameter. It is defined in the vgacon driver as nomodeset, but its set function is called text_mode() and the value queried with a function named vgacon_text_force().
All this implies that it's about forcing text mode for VGA, yet it is not used in neither vgacon nor other console driver. The only users for these are DRM drivers, that check for the vgacon_text_force() return value to determine whether the driver should be loaded or not.
That makes it quite confusing to read the code, because the variables and function names don't reflect what they actually do and also are not in the same subsystem as the drivers that make use of them.
This patch-set attempts to cleanup the code by moving the nomodseset param to the DRM subsystem and do some renaming to make their intention clearer.
This is a v4 of the patches, that address issues pointed out by Thomas Zimmermann in v3: https://lkml.org/lkml/2021/11/8/384
Patch #1 and #2 are just trivial cleanups.
Patch #3 moves the nomodeset boot option to the DRM subsystem and renames the variables and functions names.
Patch #4 removes the relationship between the nomodeset parameter and the CONFIG_VGA_CONSOLE Kconfig symbol.
Patch #5 adds nomodeset to the kernel parameters documentation.
Patch #6 improves the message when nomodeset is enabled to make it more accurate and less sensational.
Changes in v4: - Don't mention the simpledrm driver and instead explain in high level terms what the nomodeset option is about. - Don't mention DRM drivers in the kernel message and instead explain that only the system framebuffer will be available.
Changes in v3: - Drop the drm_drv_enabled() function and just call to drm_get_modeset(). - Make drm_get_modeset() just a getter function and don't return an error. - Move independent cleanups in drivers as separate preparatory patches.
Changes in v2: - Conditionally build drm_nomodeset.o if CONFIG_VGA_CONSOLE is set. - Squash patches to move nomodeset logic to DRM and do the renaming. - Name the function drm_check_modeset() and make it return -ENODEV. - Squash patch to add drm_drv_enabled() and make drivers use it. - Make the drivers changes before moving nomodeset logic to DRM. - Make drm_drv_enabled() return an errno and -ENODEV if nomodeset. - Remove debug and error messages in drivers.
Javier Martinez Canillas (6): drm: Don't print messages if drivers are disabled due nomodeset drm/vboxvideo: Drop CONFIG_VGA_CONSOLE guard to call vgacon_text_force() drm: Move nomodeset kernel parameter to the DRM subsystem drm: Decouple nomodeset from CONFIG_VGA_CONSOLE Documentation/admin-guide: Document nomodeset kernel parameter drm: Make the nomodeset message less sensational
.../admin-guide/kernel-parameters.txt | 7 ++++++ drivers/gpu/drm/Kconfig | 6 +++++ drivers/gpu/drm/Makefile | 2 ++ drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 6 ++--- drivers/gpu/drm/ast/ast_drv.c | 4 ++-- drivers/gpu/drm/drm_nomodeset.c | 24 +++++++++++++++++++ drivers/gpu/drm/i915/i915_module.c | 4 ++-- drivers/gpu/drm/mgag200/mgag200_drv.c | 4 ++-- drivers/gpu/drm/nouveau/nouveau_drm.c | 4 ++-- drivers/gpu/drm/qxl/qxl_drv.c | 4 ++-- drivers/gpu/drm/radeon/radeon_drv.c | 10 +++----- drivers/gpu/drm/tiny/bochs.c | 4 ++-- drivers/gpu/drm/tiny/cirrus.c | 5 ++-- drivers/gpu/drm/vboxvideo/vbox_drv.c | 6 ++--- drivers/gpu/drm/virtio/virtgpu_drv.c | 4 ++-- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 4 ++-- drivers/video/console/vgacon.c | 21 ---------------- include/drm/drm_mode_config.h | 2 ++ include/linux/console.h | 6 ----- 19 files changed, 67 insertions(+), 60 deletions(-) create mode 100644 drivers/gpu/drm/drm_nomodeset.c
The nomodeset kernel parameter handler already prints a message that the DRM drivers will be disabled, so there's no need for drivers to do that.
Suggested-by: Thomas Zimmermann tzimmermann@suse.de Signed-off-by: Javier Martinez Canillas javierm@redhat.com Acked-by: Thomas Zimmermann tzimmermann@suse.de ---
(no changes since v1)
drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 4 +--- drivers/gpu/drm/radeon/radeon_drv.c | 8 ++------ 2 files changed, 3 insertions(+), 9 deletions(-)
diff --git drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c index c718fb5f3f8a..289d04999ced 100644 --- drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c +++ drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c @@ -2514,10 +2514,8 @@ static int __init amdgpu_init(void) { int r;
- if (vgacon_text_force()) { - DRM_ERROR("VGACON disables amdgpu kernel modesetting.\n"); + if (vgacon_text_force()) return -EINVAL; - }
r = amdgpu_sync_init(); if (r) diff --git drivers/gpu/drm/radeon/radeon_drv.c drivers/gpu/drm/radeon/radeon_drv.c index b74cebca1f89..380adc61e71c 100644 --- drivers/gpu/drm/radeon/radeon_drv.c +++ drivers/gpu/drm/radeon/radeon_drv.c @@ -637,15 +637,11 @@ static struct pci_driver radeon_kms_pci_driver = {
static int __init radeon_module_init(void) { - if (vgacon_text_force() && radeon_modeset == -1) { - DRM_INFO("VGACON disable radeon kernel modesetting.\n"); + if (vgacon_text_force() && radeon_modeset == -1) radeon_modeset = 0; - }
- if (radeon_modeset == 0) { - DRM_ERROR("No UMS support in radeon module!\n"); + if (radeon_modeset == 0) return -EINVAL; - }
DRM_INFO("radeon kernel modesetting enabled.\n"); radeon_register_atpx_handler();
It is already handled by the console.h macro since a stub inline function is defined for vgacon_text_force() if CONFIG_VGA_CONSOLE is not set.
There's no need to have ifdefery in the driver when calling the function.
Signed-off-by: Javier Martinez Canillas javierm@redhat.com Acked-by: Thomas Zimmermann tzimmermann@suse.de ---
(no changes since v1)
drivers/gpu/drm/vboxvideo/vbox_drv.c | 2 -- 1 file changed, 2 deletions(-)
diff --git drivers/gpu/drm/vboxvideo/vbox_drv.c drivers/gpu/drm/vboxvideo/vbox_drv.c index a6c81af37345..fd7abb029c65 100644 --- drivers/gpu/drm/vboxvideo/vbox_drv.c +++ drivers/gpu/drm/vboxvideo/vbox_drv.c @@ -193,10 +193,8 @@ static const struct drm_driver driver = {
static int __init vbox_init(void) { -#ifdef CONFIG_VGA_CONSOLE if (vgacon_text_force() && vbox_modeset == -1) return -EINVAL; -#endif
if (vbox_modeset == 0) return -EINVAL;
The "nomodeset" kernel cmdline parameter is handled by the vgacon driver but the exported vgacon_text_force() symbol is only used by DRM drivers.
It makes much more sense for the parameter logic to be in the subsystem of the drivers that are making use of it.
Let's move the vgacon_text_force() function and related logic to the DRM subsystem. While doing that, rename the function to drm_get_modeset() and make it return true if modesetting is enabled and false otherwise. This better reflects the condition that drivers are actually testing for.
Suggested-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Javier Martinez Canillas javierm@redhat.com Acked-by: Thomas Zimmermann tzimmermann@suse.de ---
(no changes since v3)
Changes in v3: - Drop the drm_drv_enabled() function and just call to drm_get_modeset(). - Make drm_get_modeset() just a getter function and don't return an error. - Move independent cleanups in drivers as separate preparatory patches.
Changes in v2: - Conditionally build drm_nomodeset.o if CONFIG_VGA_CONSOLE is set. - Squash patches to move nomodeset logic to DRM and do the renaming. - Name the function drm_check_modeset() and make it return -ENODEV. - Squash patch to add drm_drv_enabled() and make drivers use it. - Make the drivers changes before moving nomodeset logic to DRM. - Make drm_drv_enabled() return an errno and -ENODEV if nomodeset. - Remove debug and error messages in drivers.
drivers/gpu/drm/Makefile | 2 ++ drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 4 ++-- drivers/gpu/drm/ast/ast_drv.c | 4 ++-- drivers/gpu/drm/drm_nomodeset.c | 26 +++++++++++++++++++++++++ drivers/gpu/drm/i915/i915_module.c | 4 ++-- drivers/gpu/drm/mgag200/mgag200_drv.c | 4 ++-- drivers/gpu/drm/nouveau/nouveau_drm.c | 4 ++-- drivers/gpu/drm/qxl/qxl_drv.c | 4 ++-- drivers/gpu/drm/radeon/radeon_drv.c | 4 ++-- drivers/gpu/drm/tiny/bochs.c | 4 ++-- drivers/gpu/drm/tiny/cirrus.c | 5 +++-- drivers/gpu/drm/vboxvideo/vbox_drv.c | 4 ++-- drivers/gpu/drm/virtio/virtgpu_drv.c | 4 ++-- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 4 ++-- drivers/video/console/vgacon.c | 21 -------------------- include/drm/drm_mode_config.h | 6 ++++++ include/linux/console.h | 6 ------ 17 files changed, 59 insertions(+), 51 deletions(-) create mode 100644 drivers/gpu/drm/drm_nomodeset.c
diff --git drivers/gpu/drm/Makefile drivers/gpu/drm/Makefile index 1c41156deb5f..c74810c285af 100644 --- drivers/gpu/drm/Makefile +++ drivers/gpu/drm/Makefile @@ -33,6 +33,8 @@ drm-$(CONFIG_DRM_PRIVACY_SCREEN) += drm_privacy_screen.o drm_privacy_screen_x86.
obj-$(CONFIG_DRM_DP_AUX_BUS) += drm_dp_aux_bus.o
+obj-$(CONFIG_VGA_CONSOLE) += drm_nomodeset.o + drm_cma_helper-y := drm_gem_cma_helper.o obj-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_cma_helper.o
diff --git drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c index 289d04999ced..0da7f0b14700 100644 --- drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c +++ drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c @@ -28,10 +28,10 @@ #include <drm/drm_gem.h> #include <drm/drm_vblank.h> #include <drm/drm_managed.h> +#include <drm/drm_mode_config.h> #include "amdgpu_drv.h"
#include <drm/drm_pciids.h> -#include <linux/console.h> #include <linux/module.h> #include <linux/pm_runtime.h> #include <linux/vga_switcheroo.h> @@ -2514,7 +2514,7 @@ static int __init amdgpu_init(void) { int r;
- if (vgacon_text_force()) + if (!drm_get_modeset()) return -EINVAL;
r = amdgpu_sync_init(); diff --git drivers/gpu/drm/ast/ast_drv.c drivers/gpu/drm/ast/ast_drv.c index 86d5cd7b6318..e788deac15cb 100644 --- drivers/gpu/drm/ast/ast_drv.c +++ drivers/gpu/drm/ast/ast_drv.c @@ -26,7 +26,6 @@ * Authors: Dave Airlie airlied@redhat.com */
-#include <linux/console.h> #include <linux/module.h> #include <linux/pci.h>
@@ -35,6 +34,7 @@ #include <drm/drm_crtc_helper.h> #include <drm/drm_drv.h> #include <drm/drm_gem_vram_helper.h> +#include <drm/drm_mode_config.h> #include <drm/drm_probe_helper.h>
#include "ast_drv.h" @@ -233,7 +233,7 @@ static struct pci_driver ast_pci_driver = {
static int __init ast_init(void) { - if (vgacon_text_force() && ast_modeset == -1) + if (!drm_get_modeset() && ast_modeset == -1) return -EINVAL;
if (ast_modeset == 0) diff --git drivers/gpu/drm/drm_nomodeset.c drivers/gpu/drm/drm_nomodeset.c new file mode 100644 index 000000000000..fc3acf3ab2e2 --- /dev/null +++ drivers/gpu/drm/drm_nomodeset.c @@ -0,0 +1,26 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/module.h> +#include <linux/types.h> + +static bool drm_nomodeset; + +bool drm_get_modeset(void) +{ + return !drm_nomodeset; +} +EXPORT_SYMBOL(drm_get_modeset); + +static int __init disable_modeset(char *str) +{ + drm_nomodeset = true; + + pr_warn("You have booted with nomodeset. This means your GPU drivers are DISABLED\n"); + pr_warn("Any video related functionality will be severely degraded, and you may not even be able to suspend the system properly\n"); + pr_warn("Unless you actually understand what nomodeset does, you should reboot without enabling it\n"); + + return 1; +} + +/* Disable kernel modesetting */ +__setup("nomodeset", disable_modeset); diff --git drivers/gpu/drm/i915/i915_module.c drivers/gpu/drm/i915/i915_module.c index ab2295dd4500..f952e8b69465 100644 --- drivers/gpu/drm/i915/i915_module.c +++ drivers/gpu/drm/i915/i915_module.c @@ -4,7 +4,7 @@ * Copyright © 2021 Intel Corporation */
-#include <linux/console.h> +#include <drm/drm_mode_config.h>
#include "gem/i915_gem_context.h" #include "gem/i915_gem_object.h" @@ -31,7 +31,7 @@ static int i915_check_nomodeset(void) if (i915_modparams.modeset == 0) use_kms = false;
- if (vgacon_text_force() && i915_modparams.modeset == -1) + if (!drm_get_modeset() && i915_modparams.modeset == -1) use_kms = false;
if (!use_kms) { diff --git drivers/gpu/drm/mgag200/mgag200_drv.c drivers/gpu/drm/mgag200/mgag200_drv.c index 6b9243713b3c..3df5a608d0e7 100644 --- drivers/gpu/drm/mgag200/mgag200_drv.c +++ drivers/gpu/drm/mgag200/mgag200_drv.c @@ -6,7 +6,6 @@ * Dave Airlie */
-#include <linux/console.h> #include <linux/module.h> #include <linux/pci.h> #include <linux/vmalloc.h> @@ -15,6 +14,7 @@ #include <drm/drm_drv.h> #include <drm/drm_file.h> #include <drm/drm_ioctl.h> +#include <drm/drm_mode_config.h> #include <drm/drm_pciids.h>
#include "mgag200_drv.h" @@ -378,7 +378,7 @@ static struct pci_driver mgag200_pci_driver = {
static int __init mgag200_init(void) { - if (vgacon_text_force() && mgag200_modeset == -1) + if (!drm_get_modeset() && mgag200_modeset == -1) return -EINVAL;
if (mgag200_modeset == 0) diff --git drivers/gpu/drm/nouveau/nouveau_drm.c drivers/gpu/drm/nouveau/nouveau_drm.c index 1f828c9f691c..d42e07de6460 100644 --- drivers/gpu/drm/nouveau/nouveau_drm.c +++ drivers/gpu/drm/nouveau/nouveau_drm.c @@ -22,7 +22,6 @@ * Authors: Ben Skeggs */
-#include <linux/console.h> #include <linux/delay.h> #include <linux/module.h> #include <linux/pci.h> @@ -34,6 +33,7 @@ #include <drm/drm_crtc_helper.h> #include <drm/drm_gem_ttm_helper.h> #include <drm/drm_ioctl.h> +#include <drm/drm_mode_config.h> #include <drm/drm_vblank.h>
#include <core/gpuobj.h> @@ -1322,7 +1322,7 @@ nouveau_drm_init(void) nouveau_display_options();
if (nouveau_modeset == -1) { - if (vgacon_text_force()) + if (!drm_get_modeset()) nouveau_modeset = 0; }
diff --git drivers/gpu/drm/qxl/qxl_drv.c drivers/gpu/drm/qxl/qxl_drv.c index fc47b0deb021..2d87a95ae431 100644 --- drivers/gpu/drm/qxl/qxl_drv.c +++ drivers/gpu/drm/qxl/qxl_drv.c @@ -29,7 +29,6 @@
#include "qxl_drv.h"
-#include <linux/console.h> #include <linux/module.h> #include <linux/pci.h> #include <linux/vgaarb.h> @@ -40,6 +39,7 @@ #include <drm/drm_drv.h> #include <drm/drm_file.h> #include <drm/drm_gem_ttm_helper.h> +#include <drm/drm_mode_config.h> #include <drm/drm_modeset_helper.h> #include <drm/drm_prime.h> #include <drm/drm_probe_helper.h> @@ -295,7 +295,7 @@ static struct drm_driver qxl_driver = {
static int __init qxl_init(void) { - if (vgacon_text_force() && qxl_modeset == -1) + if (!drm_get_modeset() && qxl_modeset == -1) return -EINVAL;
if (qxl_modeset == 0) diff --git drivers/gpu/drm/radeon/radeon_drv.c drivers/gpu/drm/radeon/radeon_drv.c index 380adc61e71c..802a28d55d0a 100644 --- drivers/gpu/drm/radeon/radeon_drv.c +++ drivers/gpu/drm/radeon/radeon_drv.c @@ -31,7 +31,6 @@
#include <linux/compat.h> -#include <linux/console.h> #include <linux/module.h> #include <linux/pm_runtime.h> #include <linux/vga_switcheroo.h> @@ -45,6 +44,7 @@ #include <drm/drm_file.h> #include <drm/drm_gem.h> #include <drm/drm_ioctl.h> +#include <drm/drm_mode_config.h> #include <drm/drm_pciids.h> #include <drm/drm_probe_helper.h> #include <drm/drm_vblank.h> @@ -637,7 +637,7 @@ static struct pci_driver radeon_kms_pci_driver = {
static int __init radeon_module_init(void) { - if (vgacon_text_force() && radeon_modeset == -1) + if (!drm_get_modeset() && radeon_modeset == -1) radeon_modeset = 0;
if (radeon_modeset == 0) diff --git drivers/gpu/drm/tiny/bochs.c drivers/gpu/drm/tiny/bochs.c index 2ce3bd903b70..500101f8a6e9 100644 --- drivers/gpu/drm/tiny/bochs.c +++ drivers/gpu/drm/tiny/bochs.c @@ -1,6 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-or-later
-#include <linux/console.h> #include <linux/pci.h>
#include <drm/drm_aperture.h> @@ -11,6 +10,7 @@ #include <drm/drm_gem_framebuffer_helper.h> #include <drm/drm_gem_vram_helper.h> #include <drm/drm_managed.h> +#include <drm/drm_mode_config.h> #include <drm/drm_probe_helper.h> #include <drm/drm_simple_kms_helper.h>
@@ -719,7 +719,7 @@ static struct pci_driver bochs_pci_driver = {
static int __init bochs_init(void) { - if (vgacon_text_force() && bochs_modeset == -1) + if (!drm_get_modeset() && bochs_modeset == -1) return -EINVAL;
if (bochs_modeset == 0) diff --git drivers/gpu/drm/tiny/cirrus.c drivers/gpu/drm/tiny/cirrus.c index 4611ec408506..c94a030b6b3b 100644 --- drivers/gpu/drm/tiny/cirrus.c +++ drivers/gpu/drm/tiny/cirrus.c @@ -16,7 +16,6 @@ * Copyright 1999-2001 Jeff Garzik jgarzik@pobox.com */
-#include <linux/console.h> #include <linux/dma-buf-map.h> #include <linux/module.h> #include <linux/pci.h> @@ -39,6 +38,7 @@ #include <drm/drm_gem_shmem_helper.h> #include <drm/drm_ioctl.h> #include <drm/drm_managed.h> +#include <drm/drm_mode_config.h> #include <drm/drm_modeset_helper_vtables.h> #include <drm/drm_probe_helper.h> #include <drm/drm_simple_kms_helper.h> @@ -636,8 +636,9 @@ static struct pci_driver cirrus_pci_driver = {
static int __init cirrus_init(void) { - if (vgacon_text_force()) + if (!drm_get_modeset()) return -EINVAL; + return pci_register_driver(&cirrus_pci_driver); }
diff --git drivers/gpu/drm/vboxvideo/vbox_drv.c drivers/gpu/drm/vboxvideo/vbox_drv.c index fd7abb029c65..74b8c93a664f 100644 --- drivers/gpu/drm/vboxvideo/vbox_drv.c +++ drivers/gpu/drm/vboxvideo/vbox_drv.c @@ -7,7 +7,6 @@ * Michael Thayer <michael.thayer@oracle.com, * Hans de Goede hdegoede@redhat.com */ -#include <linux/console.h> #include <linux/module.h> #include <linux/pci.h> #include <linux/vt_kern.h> @@ -19,6 +18,7 @@ #include <drm/drm_file.h> #include <drm/drm_ioctl.h> #include <drm/drm_managed.h> +#include <drm/drm_mode_config.h>
#include "vbox_drv.h"
@@ -193,7 +193,7 @@ static const struct drm_driver driver = {
static int __init vbox_init(void) { - if (vgacon_text_force() && vbox_modeset == -1) + if (!drm_get_modeset() && vbox_modeset == -1) return -EINVAL;
if (vbox_modeset == 0) diff --git drivers/gpu/drm/virtio/virtgpu_drv.c drivers/gpu/drm/virtio/virtgpu_drv.c index 749db18dcfa2..6ad20c225eed 100644 --- drivers/gpu/drm/virtio/virtgpu_drv.c +++ drivers/gpu/drm/virtio/virtgpu_drv.c @@ -27,7 +27,6 @@ */
#include <linux/module.h> -#include <linux/console.h> #include <linux/pci.h> #include <linux/poll.h> #include <linux/wait.h> @@ -37,6 +36,7 @@ #include <drm/drm_atomic_helper.h> #include <drm/drm_drv.h> #include <drm/drm_file.h> +#include <drm/drm_mode_config.h>
#include "virtgpu_drv.h"
@@ -104,7 +104,7 @@ static int virtio_gpu_probe(struct virtio_device *vdev) struct drm_device *dev; int ret;
- if (vgacon_text_force() && virtio_gpu_modeset == -1) + if (!drm_get_modeset() && virtio_gpu_modeset == -1) return -EINVAL;
if (virtio_gpu_modeset == 0) diff --git drivers/gpu/drm/vmwgfx/vmwgfx_drv.c drivers/gpu/drm/vmwgfx/vmwgfx_drv.c index ab9a1750e1df..049fd017dca5 100644 --- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c +++ drivers/gpu/drm/vmwgfx/vmwgfx_drv.c @@ -25,7 +25,6 @@ * **************************************************************************/
-#include <linux/console.h> #include <linux/dma-mapping.h> #include <linux/module.h> #include <linux/pci.h> @@ -34,6 +33,7 @@ #include <drm/drm_aperture.h> #include <drm/drm_drv.h> #include <drm/drm_ioctl.h> +#include <drm/drm_mode_config.h> #include <drm/drm_sysfs.h> #include <drm/ttm/ttm_bo_driver.h> #include <drm/ttm/ttm_range_manager.h> @@ -1651,7 +1651,7 @@ static int __init vmwgfx_init(void) { int ret;
- if (vgacon_text_force()) + if (!drm_get_modeset()) return -EINVAL;
ret = pci_register_driver(&vmw_pci_driver); diff --git drivers/video/console/vgacon.c drivers/video/console/vgacon.c index ef9c57ce0906..d4320b147956 100644 --- drivers/video/console/vgacon.c +++ drivers/video/console/vgacon.c @@ -97,30 +97,9 @@ static int vga_video_font_height; static int vga_scan_lines __read_mostly; static unsigned int vga_rolled_over; /* last vc_origin offset before wrap */
-static bool vgacon_text_mode_force; static bool vga_hardscroll_enabled; static bool vga_hardscroll_user_enable = true;
-bool vgacon_text_force(void) -{ - return vgacon_text_mode_force; -} -EXPORT_SYMBOL(vgacon_text_force); - -static int __init text_mode(char *str) -{ - vgacon_text_mode_force = true; - - pr_warn("You have booted with nomodeset. This means your GPU drivers are DISABLED\n"); - pr_warn("Any video related functionality will be severely degraded, and you may not even be able to suspend the system properly\n"); - pr_warn("Unless you actually understand what nomodeset does, you should reboot without enabling it\n"); - - return 1; -} - -/* force text mode - used by kernel modesetting */ -__setup("nomodeset", text_mode); - static int __init no_scroll(char *str) { /* diff --git include/drm/drm_mode_config.h include/drm/drm_mode_config.h index 48b7de80daf5..f4d407908348 100644 --- include/drm/drm_mode_config.h +++ include/drm/drm_mode_config.h @@ -969,4 +969,10 @@ static inline int drm_mode_config_init(struct drm_device *dev) void drm_mode_config_reset(struct drm_device *dev); void drm_mode_config_cleanup(struct drm_device *dev);
+#ifdef CONFIG_VGA_CONSOLE +extern bool drm_get_modeset(void); +#else +static inline bool drm_get_modeset(void) { return true; } +#endif + #endif diff --git include/linux/console.h include/linux/console.h index 20874db50bc8..d4dd8384898b 100644 --- include/linux/console.h +++ include/linux/console.h @@ -217,12 +217,6 @@ extern atomic_t ignore_console_lock_warning; #define VESA_HSYNC_SUSPEND 2 #define VESA_POWERDOWN 3
-#ifdef CONFIG_VGA_CONSOLE -extern bool vgacon_text_force(void); -#else -static inline bool vgacon_text_force(void) { return false; } -#endif - extern void console_init(void);
/* For deferred console takeover */
This relationship was only for historical reasons and the nomodeset option should be available even on platforms that don't enable CONFIG_VGA_CONSOLE.
Suggested-by: Thomas Zimmermann tzimmermann@suse.de Signed-off-by: Javier Martinez Canillas javierm@redhat.com Acked-by: Thomas Zimmermann tzimmermann@suse.de ---
(no changes since v1)
drivers/gpu/drm/Kconfig | 6 ++++++ drivers/gpu/drm/Makefile | 2 +- include/drm/drm_mode_config.h | 4 ---- 3 files changed, 7 insertions(+), 5 deletions(-)
diff --git drivers/gpu/drm/Kconfig drivers/gpu/drm/Kconfig index fb144617055b..483d534eb074 100644 --- drivers/gpu/drm/Kconfig +++ drivers/gpu/drm/Kconfig @@ -8,6 +8,7 @@ menuconfig DRM tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)" depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA + select DRM_NOMODESET select DRM_PANEL_ORIENTATION_QUIRKS select HDMI select FB_CMDLINE @@ -493,6 +494,11 @@ config DRM_EXPORT_FOR_TESTS config DRM_PANEL_ORIENTATION_QUIRKS tristate
+# Separate option because nomodeset parameter is global and expected built-in +config DRM_NOMODESET + bool + default n + config DRM_LIB_RANDOM bool default n diff --git drivers/gpu/drm/Makefile drivers/gpu/drm/Makefile index c74810c285af..fa16d3e0bbdc 100644 --- drivers/gpu/drm/Makefile +++ drivers/gpu/drm/Makefile @@ -33,7 +33,7 @@ drm-$(CONFIG_DRM_PRIVACY_SCREEN) += drm_privacy_screen.o drm_privacy_screen_x86.
obj-$(CONFIG_DRM_DP_AUX_BUS) += drm_dp_aux_bus.o
-obj-$(CONFIG_VGA_CONSOLE) += drm_nomodeset.o +obj-$(CONFIG_DRM_NOMODESET) += drm_nomodeset.o
drm_cma_helper-y := drm_gem_cma_helper.o obj-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_cma_helper.o diff --git include/drm/drm_mode_config.h include/drm/drm_mode_config.h index f4d407908348..4bb129040185 100644 --- include/drm/drm_mode_config.h +++ include/drm/drm_mode_config.h @@ -969,10 +969,6 @@ static inline int drm_mode_config_init(struct drm_device *dev) void drm_mode_config_reset(struct drm_device *dev); void drm_mode_config_cleanup(struct drm_device *dev);
-#ifdef CONFIG_VGA_CONSOLE extern bool drm_get_modeset(void); -#else -static inline bool drm_get_modeset(void) { return true; } -#endif
#endif
The nomodeset kernel command line parameter is not documented. Its name is quite vague and is not intuitive what's the behaviour when it is set.
Document in kernel-parameters.txt what actually happens when nomodeset is used. That way, users could know if they want to enable this option.
Signed-off-by: Javier Martinez Canillas javierm@redhat.com ---
Changes in v4: - Don't mention the simpledrm driver and instead explain in high level terms what the nomodeset option is about.
Documentation/admin-guide/kernel-parameters.txt | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git Documentation/admin-guide/kernel-parameters.txt Documentation/admin-guide/kernel-parameters.txt index 91ba391f9b32..f6434aff943d 100644 --- Documentation/admin-guide/kernel-parameters.txt +++ Documentation/admin-guide/kernel-parameters.txt @@ -3521,6 +3521,13 @@ shutdown the other cpus. Instead use the REBOOT_VECTOR irq.
+ nomodeset Disable kernel modesetting. DRM drivers will not perform + display-mode changes or accelerated rendering. Only the + system framebuffer will be available for use if this was + set-up by the firmware or boot loader. + + Useful as fallback, or for testing and debugging. + nomodule Disable module load
nopat [X86] Disable PAT (page attribute table extension of
The message printed when nomodeset is present in the kernel command line makes it look as if the parameter must never be used and it's a bad idea.
But there are valid reasons to use this parameter and the message should not imply otherwise. Change the text to be more accurate and restrained.
Suggested-by: Thomas Zimmermann tzimmermann@suse.de Signed-off-by: Javier Martinez Canillas javierm@redhat.com ---
Changes in v4: - Don't mention DRM drivers in the kernel message and instead explain that only the system framebuffer will be available.
drivers/gpu/drm/drm_nomodeset.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git drivers/gpu/drm/drm_nomodeset.c drivers/gpu/drm/drm_nomodeset.c index fc3acf3ab2e2..148b01f7183b 100644 --- drivers/gpu/drm/drm_nomodeset.c +++ drivers/gpu/drm/drm_nomodeset.c @@ -15,9 +15,7 @@ static int __init disable_modeset(char *str) { drm_nomodeset = true;
- pr_warn("You have booted with nomodeset. This means your GPU drivers are DISABLED\n"); - pr_warn("Any video related functionality will be severely degraded, and you may not even be able to suspend the system properly\n"); - pr_warn("Unless you actually understand what nomodeset does, you should reboot without enabling it\n"); + pr_warn("Booted with the nomodeset parameter. Only the system framebuffer will be available\n");
return 1; }
Hi
Am 08.11.21 um 15:06 schrieb Javier Martinez Canillas:
There is a lot of historical baggage on this parameter. It is defined in the vgacon driver as nomodeset, but its set function is called text_mode() and the value queried with a function named vgacon_text_force().
All this implies that it's about forcing text mode for VGA, yet it is not used in neither vgacon nor other console driver. The only users for these are DRM drivers, that check for the vgacon_text_force() return value to determine whether the driver should be loaded or not.
That makes it quite confusing to read the code, because the variables and function names don't reflect what they actually do and also are not in the same subsystem as the drivers that make use of them.
This patch-set attempts to cleanup the code by moving the nomodseset param to the DRM subsystem and do some renaming to make their intention clearer.
This is a v4 of the patches, that address issues pointed out by Thomas Zimmermann in v3: https://lkml.org/lkml/2021/11/8/384
Patch #1 and #2 are just trivial cleanups.
Patch #3 moves the nomodeset boot option to the DRM subsystem and renames the variables and functions names.
Patch #4 removes the relationship between the nomodeset parameter and the CONFIG_VGA_CONSOLE Kconfig symbol.
Patch #5 adds nomodeset to the kernel parameters documentation.
Patch #6 improves the message when nomodeset is enabled to make it more accurate and less sensational.
Acked-by: Thomas Zimmermann tzimmermann@suse.de
Best regards Thomas
Changes in v4:
- Don't mention the simpledrm driver and instead explain in high level terms what the nomodeset option is about.
- Don't mention DRM drivers in the kernel message and instead explain that only the system framebuffer will be available.
Changes in v3:
- Drop the drm_drv_enabled() function and just call to drm_get_modeset().
- Make drm_get_modeset() just a getter function and don't return an error.
- Move independent cleanups in drivers as separate preparatory patches.
Changes in v2:
- Conditionally build drm_nomodeset.o if CONFIG_VGA_CONSOLE is set.
- Squash patches to move nomodeset logic to DRM and do the renaming.
- Name the function drm_check_modeset() and make it return -ENODEV.
- Squash patch to add drm_drv_enabled() and make drivers use it.
- Make the drivers changes before moving nomodeset logic to DRM.
- Make drm_drv_enabled() return an errno and -ENODEV if nomodeset.
- Remove debug and error messages in drivers.
Javier Martinez Canillas (6): drm: Don't print messages if drivers are disabled due nomodeset drm/vboxvideo: Drop CONFIG_VGA_CONSOLE guard to call vgacon_text_force() drm: Move nomodeset kernel parameter to the DRM subsystem drm: Decouple nomodeset from CONFIG_VGA_CONSOLE Documentation/admin-guide: Document nomodeset kernel parameter drm: Make the nomodeset message less sensational
.../admin-guide/kernel-parameters.txt | 7 ++++++ drivers/gpu/drm/Kconfig | 6 +++++ drivers/gpu/drm/Makefile | 2 ++ drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 6 ++--- drivers/gpu/drm/ast/ast_drv.c | 4 ++-- drivers/gpu/drm/drm_nomodeset.c | 24 +++++++++++++++++++ drivers/gpu/drm/i915/i915_module.c | 4 ++-- drivers/gpu/drm/mgag200/mgag200_drv.c | 4 ++-- drivers/gpu/drm/nouveau/nouveau_drm.c | 4 ++-- drivers/gpu/drm/qxl/qxl_drv.c | 4 ++-- drivers/gpu/drm/radeon/radeon_drv.c | 10 +++----- drivers/gpu/drm/tiny/bochs.c | 4 ++-- drivers/gpu/drm/tiny/cirrus.c | 5 ++-- drivers/gpu/drm/vboxvideo/vbox_drv.c | 6 ++--- drivers/gpu/drm/virtio/virtgpu_drv.c | 4 ++-- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 4 ++-- drivers/video/console/vgacon.c | 21 ---------------- include/drm/drm_mode_config.h | 2 ++ include/linux/console.h | 6 ----- 19 files changed, 67 insertions(+), 60 deletions(-) create mode 100644 drivers/gpu/drm/drm_nomodeset.c
On Mon, 8 Nov 2021 15:17:13 +0100 Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 08.11.21 um 15:06 schrieb Javier Martinez Canillas:
There is a lot of historical baggage on this parameter. It is defined in the vgacon driver as nomodeset, but its set function is called text_mode() and the value queried with a function named vgacon_text_force().
All this implies that it's about forcing text mode for VGA, yet it is not used in neither vgacon nor other console driver. The only users for these are DRM drivers, that check for the vgacon_text_force() return value to determine whether the driver should be loaded or not.
That makes it quite confusing to read the code, because the variables and function names don't reflect what they actually do and also are not in the same subsystem as the drivers that make use of them.
This patch-set attempts to cleanup the code by moving the nomodseset param to the DRM subsystem and do some renaming to make their intention clearer.
This is a v4 of the patches, that address issues pointed out by Thomas Zimmermann in v3: https://lkml.org/lkml/2021/11/8/384
Patch #1 and #2 are just trivial cleanups.
Patch #3 moves the nomodeset boot option to the DRM subsystem and renames the variables and functions names.
Patch #4 removes the relationship between the nomodeset parameter and the CONFIG_VGA_CONSOLE Kconfig symbol.
Patch #5 adds nomodeset to the kernel parameters documentation.
Patch #6 improves the message when nomodeset is enabled to make it more accurate and less sensational.
Acked-by: Thomas Zimmermann tzimmermann@suse.de
Hi,
these ideas make sense to me, so FWIW,
Acked-by: Pekka Paalanen pekka.paalanen@collabora.com
There is one nitpick I'd like to ask about:
+bool drm_get_modeset(void) +{ + return !drm_nomodeset; +} +EXPORT_SYMBOL(drm_get_modeset);
Doesn't "get" have a special meaning in the kernel land, like "take a strong reference on an object and return it"?
As this is just returning bool without changing anything, the usual word to use is "is". Since this function is also used at most once per driver, which is rarely, it could have a long and descriptive name.
For example:
bool drm_is_modeset_driver_allowed(void);
- "drm" is the namespace - "is" implies it is a read-only boolean inspection - "modeset" is the feature being checked - "driver" implies it is supposed gate driver loading or initialization, rather than modesets after drivers have loaded - "allowed" says it is asking about general policy rather than what a driver does
Just a bikeshed, I'll leave it to actual kernel devs to say if this would be more appropriate or worth it.
Thanks, pq
Best regards Thomas
Changes in v4:
- Don't mention the simpledrm driver and instead explain in high level terms what the nomodeset option is about.
- Don't mention DRM drivers in the kernel message and instead explain that only the system framebuffer will be available.
Changes in v3:
- Drop the drm_drv_enabled() function and just call to drm_get_modeset().
- Make drm_get_modeset() just a getter function and don't return an error.
- Move independent cleanups in drivers as separate preparatory patches.
Changes in v2:
- Conditionally build drm_nomodeset.o if CONFIG_VGA_CONSOLE is set.
- Squash patches to move nomodeset logic to DRM and do the renaming.
- Name the function drm_check_modeset() and make it return -ENODEV.
- Squash patch to add drm_drv_enabled() and make drivers use it.
- Make the drivers changes before moving nomodeset logic to DRM.
- Make drm_drv_enabled() return an errno and -ENODEV if nomodeset.
- Remove debug and error messages in drivers.
Javier Martinez Canillas (6): drm: Don't print messages if drivers are disabled due nomodeset drm/vboxvideo: Drop CONFIG_VGA_CONSOLE guard to call vgacon_text_force() drm: Move nomodeset kernel parameter to the DRM subsystem drm: Decouple nomodeset from CONFIG_VGA_CONSOLE Documentation/admin-guide: Document nomodeset kernel parameter drm: Make the nomodeset message less sensational
.../admin-guide/kernel-parameters.txt | 7 ++++++ drivers/gpu/drm/Kconfig | 6 +++++ drivers/gpu/drm/Makefile | 2 ++ drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 6 ++--- drivers/gpu/drm/ast/ast_drv.c | 4 ++-- drivers/gpu/drm/drm_nomodeset.c | 24 +++++++++++++++++++ drivers/gpu/drm/i915/i915_module.c | 4 ++-- drivers/gpu/drm/mgag200/mgag200_drv.c | 4 ++-- drivers/gpu/drm/nouveau/nouveau_drm.c | 4 ++-- drivers/gpu/drm/qxl/qxl_drv.c | 4 ++-- drivers/gpu/drm/radeon/radeon_drv.c | 10 +++----- drivers/gpu/drm/tiny/bochs.c | 4 ++-- drivers/gpu/drm/tiny/cirrus.c | 5 ++-- drivers/gpu/drm/vboxvideo/vbox_drv.c | 6 ++--- drivers/gpu/drm/virtio/virtgpu_drv.c | 4 ++-- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 4 ++-- drivers/video/console/vgacon.c | 21 ---------------- include/drm/drm_mode_config.h | 2 ++ include/linux/console.h | 6 ----- 19 files changed, 67 insertions(+), 60 deletions(-) create mode 100644 drivers/gpu/drm/drm_nomodeset.c
Hello Pekka,
On 11/12/21 09:56, Pekka Paalanen wrote:
[snip]
Hi,
these ideas make sense to me, so FWIW,
Acked-by: Pekka Paalanen pekka.paalanen@collabora.com
Thanks.
There is one nitpick I'd like to ask about:
+bool drm_get_modeset(void) +{
return !drm_nomodeset;+} +EXPORT_SYMBOL(drm_get_modeset);
Doesn't "get" have a special meaning in the kernel land, like "take a strong reference on an object and return it"?
That's a very good point.
As this is just returning bool without changing anything, the usual word to use is "is". Since this function is also used at most once per driver, which is rarely, it could have a long and descriptive name.
For example:
bool drm_is_modeset_driver_allowed(void);
Yeah, naming is hard. Jani also mentioned that he didn't like this function name, so I don't mind to re-spin the series only for that.
- "drm" is the namespace
- "is" implies it is a read-only boolean inspection
- "modeset" is the feature being checked
- "driver" implies it is supposed gate driver loading or initialization, rather than modesets after drivers have loaded
- "allowed" says it is asking about general policy rather than what a driver does
I believe that name is more verbose than needed. But don't have a strong opinion and could use it if others agree.
Just a bikeshed, I'll leave it to actual kernel devs to say if this would be more appropriate or worth it.
I think is worth it and better to do it now before the patches land, but we could wait for others to chime in.
Best regards, -- Javier Martinez Canillas Linux Engineering Red Hat
Hi
Am 12.11.21 um 10:39 schrieb Javier Martinez Canillas:
Hello Pekka,
On 11/12/21 09:56, Pekka Paalanen wrote:
[snip]
Hi,
these ideas make sense to me, so FWIW,
Acked-by: Pekka Paalanen pekka.paalanen@collabora.com
Thanks.
There is one nitpick I'd like to ask about:
+bool drm_get_modeset(void) +{
return !drm_nomodeset;+} +EXPORT_SYMBOL(drm_get_modeset);
Doesn't "get" have a special meaning in the kernel land, like "take a strong reference on an object and return it"?
That's a very good point.
As this is just returning bool without changing anything, the usual word to use is "is". Since this function is also used at most once per driver, which is rarely, it could have a long and descriptive name.
For example:
bool drm_is_modeset_driver_allowed(void);
I'd nominate
bool drm_native_drivers_enabled()
This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Best regards Thomas
Yeah, naming is hard. Jani also mentioned that he didn't like this function name, so I don't mind to re-spin the series only for that.
- "drm" is the namespace
- "is" implies it is a read-only boolean inspection
- "modeset" is the feature being checked
- "driver" implies it is supposed gate driver loading or initialization, rather than modesets after drivers have loaded
- "allowed" says it is asking about general policy rather than what a driver does
I believe that name is more verbose than needed. But don't have a strong opinion and could use it if others agree.
Just a bikeshed, I'll leave it to actual kernel devs to say if this would be more appropriate or worth it.
I think is worth it and better to do it now before the patches land, but we could wait for others to chime in.
Best regards,
Javier Martinez Canillas Linux Engineering Red Hat
On Fri, 12 Nov 2021 11:09:13 +0100 Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 12.11.21 um 10:39 schrieb Javier Martinez Canillas:
Hello Pekka,
On 11/12/21 09:56, Pekka Paalanen wrote:
[snip]
Hi,
these ideas make sense to me, so FWIW,
Acked-by: Pekka Paalanen pekka.paalanen@collabora.com
Thanks.
There is one nitpick I'd like to ask about:
+bool drm_get_modeset(void) +{
return !drm_nomodeset;+} +EXPORT_SYMBOL(drm_get_modeset);
Doesn't "get" have a special meaning in the kernel land, like "take a strong reference on an object and return it"?
That's a very good point.
As this is just returning bool without changing anything, the usual word to use is "is". Since this function is also used at most once per driver, which is rarely, it could have a long and descriptive name.
For example:
bool drm_is_modeset_driver_allowed(void);
I'd nominate
bool drm_native_drivers_enabled()
This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Ok, but what is a "native driver"? Or a "non-native driver"? Is that established kernel terminology?
I'd think a non-native driver is something that e.g. ndiswrapper is loading. Is simpledrm like ndiswrapper in a sense? IIRC, simpledrm is the driver that would not consult this function, right?
Thanks, pq
Best regards Thomas
Yeah, naming is hard. Jani also mentioned that he didn't like this function name, so I don't mind to re-spin the series only for that.
- "drm" is the namespace
- "is" implies it is a read-only boolean inspection
- "modeset" is the feature being checked
- "driver" implies it is supposed gate driver loading or initialization, rather than modesets after drivers have loaded
- "allowed" says it is asking about general policy rather than what a driver does
I believe that name is more verbose than needed. But don't have a strong opinion and could use it if others agree.
Just a bikeshed, I'll leave it to actual kernel devs to say if this would be more appropriate or worth it.
I think is worth it and better to do it now before the patches land, but we could wait for others to chime in.
Best regards,
Javier Martinez Canillas Linux Engineering Red Hat
On 11/12/21 11:22, Pekka Paalanen wrote:
[snip]
As this is just returning bool without changing anything, the usual word to use is "is". Since this function is also used at most once per driver, which is rarely, it could have a long and descriptive name.
For example:
bool drm_is_modeset_driver_allowed(void);
I'd nominate
bool drm_native_drivers_enabled()
This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Ok, but what is a "native driver"? Or a "non-native driver"? Is that established kernel terminology?
For me the term "native" is also vague. I would prefer to call it platform specific driver or non-generic driver instead. A problem is that "platform driver" has a very specific meaning in the kernel, which are drivers for devices in the "platform" bus (which is also a very overloaded term).
I'd think a non-native driver is something that e.g. ndiswrapper is
Yeah, that's why I think that "generic" and "non-generic" is a better way to describe the drivers that could be used for any platform as long as the hardware was already initialized and a struct screen_info filled with data.
loading. Is simpledrm like ndiswrapper in a sense? IIRC, simpledrm is the driver that would not consult this function, right?
Correct.
Or maybe just 'bool drm_modeset_enabled()' ? After all, that's really what the "nomodeset" kernel param disables. The fact that DRM drivers abuse that boolean semantics to also prevent the drivers to load is a different topic.
Thanks, pq
Best regards,
On Fri, 12 Nov 2021, Pekka Paalanen ppaalanen@gmail.com wrote:
On Fri, 12 Nov 2021 11:09:13 +0100 Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 12.11.21 um 10:39 schrieb Javier Martinez Canillas:
Hello Pekka,
On 11/12/21 09:56, Pekka Paalanen wrote:
[snip]
Hi,
these ideas make sense to me, so FWIW,
Acked-by: Pekka Paalanen pekka.paalanen@collabora.com
Thanks.
There is one nitpick I'd like to ask about:
+bool drm_get_modeset(void) +{
return !drm_nomodeset;+} +EXPORT_SYMBOL(drm_get_modeset);
Doesn't "get" have a special meaning in the kernel land, like "take a strong reference on an object and return it"?
That's a very good point.
As this is just returning bool without changing anything, the usual word to use is "is". Since this function is also used at most once per driver, which is rarely, it could have a long and descriptive name.
For example:
bool drm_is_modeset_driver_allowed(void);
I'd nominate
bool drm_native_drivers_enabled()
This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Ok, but what is a "native driver"? Or a "non-native driver"? Is that established kernel terminology?
FWIW, it doesn't mean anything to me.
drm_modeset_enabled()?
*sigh* I worked so hard not to participate in this bikeshed. ;)
BR, Jani.
I'd think a non-native driver is something that e.g. ndiswrapper is loading. Is simpledrm like ndiswrapper in a sense? IIRC, simpledrm is the driver that would not consult this function, right?
Thanks, pq
Best regards Thomas
Yeah, naming is hard. Jani also mentioned that he didn't like this function name, so I don't mind to re-spin the series only for that.
- "drm" is the namespace
- "is" implies it is a read-only boolean inspection
- "modeset" is the feature being checked
- "driver" implies it is supposed gate driver loading or initialization, rather than modesets after drivers have loaded
- "allowed" says it is asking about general policy rather than what a driver does
I believe that name is more verbose than needed. But don't have a strong opinion and could use it if others agree.
Just a bikeshed, I'll leave it to actual kernel devs to say if this would be more appropriate or worth it.
I think is worth it and better to do it now before the patches land, but we could wait for others to chime in.
Best regards,
Javier Martinez Canillas Linux Engineering Red Hat
Hi
Am 12.11.21 um 11:22 schrieb Pekka Paalanen:
On Fri, 12 Nov 2021 11:09:13 +0100 Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
Am 12.11.21 um 10:39 schrieb Javier Martinez Canillas:
Hello Pekka,
On 11/12/21 09:56, Pekka Paalanen wrote:
[snip]
Hi,
these ideas make sense to me, so FWIW,
Acked-by: Pekka Paalanen pekka.paalanen@collabora.com
Thanks.
There is one nitpick I'd like to ask about:
+bool drm_get_modeset(void) +{
return !drm_nomodeset;+} +EXPORT_SYMBOL(drm_get_modeset);
Doesn't "get" have a special meaning in the kernel land, like "take a strong reference on an object and return it"?
That's a very good point.
As this is just returning bool without changing anything, the usual word to use is "is". Since this function is also used at most once per driver, which is rarely, it could have a long and descriptive name.
For example:
bool drm_is_modeset_driver_allowed(void);
I'd nominate
bool drm_native_drivers_enabled()This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Ok, but what is a "native driver"? Or a "non-native driver"? Is that established kernel terminology?
I'd think a non-native driver is something that e.g. ndiswrapper is loading. Is simpledrm like ndiswrapper in a sense? IIRC, simpledrm is the driver that would not consult this function, right?
We use that term for hw-specific drivers. A 'non-native' driver would be called generic or firmware driver.
My concern with the 'modeset' term is that it exposes an implementation detail, which can mislead a driver to to the wrong thing: a HW-specifc driver that disables it's modesetting functionality would pass the test for (!modeset). But that's not what we want, we want to disable all of the driver and not even load it.
How about we invert the test function and use something like
bool drm_firmware_drivers_only()
? HW-native drivers can do
if (drm_firmware_drivers_only()) return;
as early as possible. fbdev uses the flag FBINFO_MISC_FIRMWARE to mark rsp drivers. So the terminology is there already.
Best regards Thomas
Thanks, pq
Best regards Thomas
Yeah, naming is hard. Jani also mentioned that he didn't like this function name, so I don't mind to re-spin the series only for that.
- "drm" is the namespace
- "is" implies it is a read-only boolean inspection
- "modeset" is the feature being checked
- "driver" implies it is supposed gate driver loading or initialization, rather than modesets after drivers have loaded
- "allowed" says it is asking about general policy rather than what a driver does
I believe that name is more verbose than needed. But don't have a strong opinion and could use it if others agree.
Just a bikeshed, I'll leave it to actual kernel devs to say if this would be more appropriate or worth it.
I think is worth it and better to do it now before the patches land, but we could wait for others to chime in.
Best regards,
Javier Martinez Canillas Linux Engineering Red Hat
On 11/12/21 11:57, Thomas Zimmermann wrote:
[snip]
This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Ok, but what is a "native driver"? Or a "non-native driver"? Is that established kernel terminology?
I'd think a non-native driver is something that e.g. ndiswrapper is loading. Is simpledrm like ndiswrapper in a sense? IIRC, simpledrm is the driver that would not consult this function, right?
We use that term for hw-specific drivers. A 'non-native' driver would be called generic or firmware driver.
My concern with the 'modeset' term is that it exposes an implementation detail, which can mislead a driver to to the wrong thing: a HW-specifc driver that disables it's modesetting functionality would pass the test for (!modeset). But that's not what we want, we want to disable all of the driver and not even load it.
How about we invert the test function and use something like
bool drm_firmware_drivers_only()
That name I think is more self explanatory, so it works for me.
There was also another bikeshed about where to put the function declaration, I added to <drm/drm_mode_config.h> but with that name I believe that should be in <drm/drm_drv.h> instead.
Best regards, -- Javier Martinez Canillas Linux Engineering Red Hat
Hi
Am 12.11.21 um 12:20 schrieb Javier Martinez Canillas:
On 11/12/21 11:57, Thomas Zimmermann wrote:
[snip]
This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Ok, but what is a "native driver"? Or a "non-native driver"? Is that established kernel terminology?
I'd think a non-native driver is something that e.g. ndiswrapper is loading. Is simpledrm like ndiswrapper in a sense? IIRC, simpledrm is the driver that would not consult this function, right?
We use that term for hw-specific drivers. A 'non-native' driver would be called generic or firmware driver.
My concern with the 'modeset' term is that it exposes an implementation detail, which can mislead a driver to to the wrong thing: a HW-specifc driver that disables it's modesetting functionality would pass the test for (!modeset). But that's not what we want, we want to disable all of the driver and not even load it.
How about we invert the test function and use something like
bool drm_firmware_drivers_only()
That name I think is more self explanatory, so it works for me.
There was also another bikeshed about where to put the function declaration, I added to <drm/drm_mode_config.h> but with that name I believe that should be in <drm/drm_drv.h> instead.
I agree with drm_drv.h. It's a DRM-wide function and it fit's there best, I'd say.
Best regards Thomas
Best regards, -- Javier Martinez Canillas Linux Engineering Red Hat
On Fri, 12 Nov 2021 12:20:14 +0100 Javier Martinez Canillas javierm@redhat.com wrote:
On 11/12/21 11:57, Thomas Zimmermann wrote:
[snip]
This is what HW-specific drivers want to query in their init/probing code. The actual semantics of this decision is hidden from the driver. It's also easier to read than the other name IMHO
Ok, but what is a "native driver"? Or a "non-native driver"? Is that established kernel terminology?
I'd think a non-native driver is something that e.g. ndiswrapper is loading. Is simpledrm like ndiswrapper in a sense? IIRC, simpledrm is the driver that would not consult this function, right?
We use that term for hw-specific drivers. A 'non-native' driver would be called generic or firmware driver.
My concern with the 'modeset' term is that it exposes an implementation detail, which can mislead a driver to to the wrong thing: a HW-specifc driver that disables it's modesetting functionality would pass the test for (!modeset). But that's not what we want, we want to disable all of the driver and not even load it.
How about we invert the test function and use something like
bool drm_firmware_drivers_only()
That name I think is more self explanatory, so it works for me.
I'm not going to argue against that. :-)
Thanks, pq
dri-devel@lists.freedesktop.org
-
Jani Nikula -
Javier Martinez Canillas -
Pekka Paalanen -
Thomas Zimmermann